Spin Peierls Systems

Spin Peierls Systems

Great excitement is being generated by research on low dimensional magnetic systems because of their possible links with high temperature superconductivity.

The one dimensional antiferromagnetic system CuGeO3 is not only a spin - 1/2 system exhibiting high frequency quantum spin fluctuations, it also undergoes a structural transition. Below 14K the lattice dimerizes forming spin-singlet pairs, a so called spin-Peierls transition. This makes CuGeO3 the first inorganic material to possess such an effect. However, what makes it so interesting is the possibility that charge doping such a material may produce superconductivity.

In an experiment on MARI a 15gm multi-crystal was aligned with the incident wavevector perpendicular to the one-dimensional axis of the antiferromagnet. The results are similar to those seen for other spin-1/2 one-dimensional antiferromagnets and show the spin gap, the classical spin wave dispersion and the double spinon continuum stretching over two Brillouin zones. However, it also shows an unexpected peak at the top of the spin-wave. At present the origin of this feature remains a mystery.